6. To re-use what you have entered into the spark-shell, you can extract your input from the spark shell history which is in a file called “.spark-history” in the user’s home directory. For example `tail -n 5 .spark_history > mySession1.scala`. Next time, you can use (1) to reload your saved scala session. In the shell session, if you want to check history, you can simply do `scala> :history`

7. A library called scalaplot can help you to do some visual investigation.